#!/usr/bin/perl

# https://perlmonks.org/?node_id=1223630

use strict;
use warnings;
use Data::Dumper;
$Data::Dumper::Indent = 0;

local $/ = "\nXXX\n";
s/\nXXX\n\z//, tr/\n/ / for my @data = <DATA>;

print Dumper \@data;

__DATA__
This is a test.
XXX
This is a multiline
test.
XXX